title: Prospects and performance limitations for Cu-Zn-Sn-S-Se photovoltaic technology.
abstract: While cadmium telluride and copper-indium-gallium-sulfide-selenide (CIGSSe) solar cells have either already surpassed (for CdTe) or reached (for CIGSSe) the 1 GW yr⁻¹ production level, highlighting the promise of these rapidly growing thin-film technologies, reliance on the heavy metal cadmium and scarce elements indium and tellurium has prompted concern about scalability towards the terawatt level. Despite recent advances in structurally related copper-zinc-tin-sulfide-selenide (CZTSSe) absorbers, in which indium from CIGSSe is replaced with more plentiful and lower cost zinc and tin, there is still a sizeable performance gap between the kesterite CZTSSe and the more mature CdTe and CIGSSe technologies. This review will discuss recent progress in the CZTSSe field, especially focusing on a direct comparison with analogous higher performing CIGSSe to probe the performance bottlenecks in Earth-abundant kesterite devices. Key limitations in the current generation of CZTSSe devices include a shortfall in open circuit voltage relative to the absorber band gap and secondarily a high series resistance, which contributes to a lower device fill factor. Understanding and addressing these performance issues should yield closer performance parity between CZTSSe and CdTe/CIGSSe absorbers and hopefully facilitate a successful launch of commercialization for the kesterite-based technology.
authors.affiliation: IBM T. J. Watson Research Center, PO Box 218, Yorktown Heights, NY 10598, USA. dmitzi@us.ibm.com
authors.forename: David B
authors.initials: DB
authors.lastname: Mitzi
authors.forename: Oki
authors.initials: O
authors.lastname: Gunawan
authors.forename: Teodor K
authors.initials: TK
authors.lastname: Todorov
authors.forename: D Aaron R
authors.initials: DA
authors.lastname: Barkhouse
keywords: Cu2ZnSn(S,Se)4; Earth-abundant; kesterite; photovoltaics; thin-film solar cell